Means for controlling the operation of vapor generators



June 29, 1943. f c. SCHROEDER 2,

' Imus FOR CONTROLLING THE OPERATION OF VAPOR anummons Filed larch 22, 1939 LIQUID l/VFLOW Carl .fi'cizroeder Patented June 29, 1943 MEANS FOR CONTROLLING THE OPERATION OF VAPOR GENERATORS Carl Schroeder, Berlin, Germany; vested in the Alien Property Custodian Application March 22, 1939, Serial No. 263,494

In Germany March 22, 1938 3 Claims. (o1. 122-4512) This invention relates to a means for controlling the operation of vapor generators having a fluid passage receiving liquid at one end and delivering superheated vapor at the other end. More particularly my invention relates to the type of vapor generators in which a drum or liquid separator is connected to the passage at the end of the zone of evaporation for separating this zone of evaporation from the superheater.

The first object of my invention is to improve means for controlling the temperature of vapor. As within the drum of such vapor generators the temperature of vapor depends only on the pressure existing in the drum, a pressure regulating system is provided for maintaining a constant pressure in said drum in order to simultaneously keep constant the temperature of vapor existing in the drum.

A further object of my invention is to improve means for controlling an additional liquid inflow to the passage so as to superfeed the generator and for controlling the water level in said drum without influencing the ratio of liquid inflow to vapor outflow adjusted in a well known manner by a regulating device.

These and other objects which will be ap parent to those skilled in this particular art are obtained by the invention illustrated on the accompanying drawing in which Fig. 1 is a schematic illustration of one embodiment of the invention, and

Fig. 2 shows a diagram which will be more fully explained.

A passage system I is connected to a water feeding pump and heated by a burner I". In the feeding conduit a feed control valve 3 and an auxiliary valve 4 are provided. By means of a regulator system 5 adjusting the auxiliary valve 4 the pressure difference existing at the valve 3 is maintained constant, said system 5 being a well known Askania jet pipe relay and need, therefore, not .be more fully explained. By maintaining constant the pressure dili'erence at the control valve 3 the water inflow is only dependent on the cross section of the valve 3, i. e., on the position of the lever B. If the auxiliary valve 4 were not provided, any rocking movement of the lever B would not result only in a corresponding variation of the cross section of valve 3 but also in a variation of the pressure drop at 3, so that the water inflow, which is a function of the cross section as well as of the pressure drop, is not positively determined by the position of the lever B.

The water fedto passage l evaporates in a small drum 1 provided as water separator for collecting the separated water, said drum being inserted in the passage I, so that part 8 of the a passage serves forthe superheating of the vapor.

A measuring conduit I0 is connected to the drum 1 at point 9 and leads to a well-known bellows system H, balanced by a weight member I l and actuating a well known Askania jet pipe for controlling, by means of a servo-motor [2, a valve I3 inserted in the vapor part of passage I. By means of this arrangement the pressure existing in the drum 1 is maintained at a predetermined value, determined by a spring l4 acting upon said jet pipe in opposition to the controlling impulse exerted by said bellows ll. As there only exists saturated vapor in the drum 1 the temperature of the vapor depends upon the pressure, and as this pressure is maintained constant by the valve IE3 the temperature of the saturated vapor in the drum 1 is also maintained constant. It is an essential advantage of my invention that the saturated vapor temperature will be controlled by meansof the described pressure responsive device I I, H, l4, l2 and I3 without taking an impulse which is directly derived from the temperature of the vapor. The length of the superheater 8 being constant itis quite suflicient to maintain a constant temperature in the drum 1 in order to have a constant temperature of vapor at the end of the superheater 8.

Another measuring conduit l6 connected to the vapor'part of the passage l as at I5 leads to a bellows system I1 provided for actuating a jet pipe regulator I8 controlling the feeding valve 3. A weight l9 corresponding to the pressure to be maintained constant in the drum 1 by means of the valve l3 above referred to is provided at the regulator system I 8 for balancing the pressure acting upon the bellows system ll. By means of this arrangement it is achieved that the regulator I8 will be controlled in accordance withlan impulse eorresponding to the pressure difference between 9 and 15, i. e., to the pressure drop from 9 t0 I5. The pressure at 9 being maintained constant in the manner described, the pressure variations at l5 indicate the pressure drop and therefore the amount of superheated vapor flowing out or, in other words, the generator load variations.

Another impulse corresponding to the water inflow acts against this load impulse in a manner to be more fully explained. Therefore, by means of the regulator l8 the water inflow through the valve 3 is adjusted in accordance with the vapor outflow or generator load.

The regulator I8 comprises a jet pipe relay for controlling a servo-motor 20, the piston rod 2! of which is operatively connected to the valve lever B. In addition the piston rod 2| is provided with a cam 22 for varying the tension of a spring 26 acting on the jet pipe relay in response to the position of the servo-motor 20 or of the valve lever 6. As will be readily understood, the function of this variation of the spring tension is determined by the curvature of'the cam 22. Therefore this function may be determined by the selection of the cam curvature. If desired, the cam 22' may be made so as to be easily adjustable so that it is possible to change the cam curvature as required. By means of a variation of the cam curvature it is further pos sible to take into account the characteristic of the valve 3 and of any influence of changes in load on the pressure at I 5, i.. e., the pressure the variations of which represent load variations.

From the foregoing it follows that the relation between. the position of the valve lever B or the water'infiow and the load variations corresponds to the curvature of the cam 22. Therefore the ratio of the water inflow and the vapor outflow may be influenced by the curvature of cam 22. According'to theinvention the curvature of cam 22 may be such that at every load an additional quantity of water is suppliedto the passage which does not leave it as vapor, the excess of water being collected in the drum 1, there forming a water level 1.

Referring to Fig. 2 the linesv a, a, a" represent the ratio: water inflow-vapor outflow. The angular deflection of these lines a, a, a depends upon the position of the so-called ratio slider l8 of the regulator IS. The middle position of said ratio slider l8 as shown in the drawing results in the characteristic a, i. e., a characteristic according to which the water inflow is equal to the vapor outflow at all generator loads. Therefore the characteristic a signifies a water supply at all generator loads and is smaller than the vapor outflow, whilst according to the characteristic the superfeed of water increases upon an increase of load, it being understood that the vertical distance between the characteristics a" and a increases the more, the more the load or' the vapor outflow increases.- In case an additional force as, e. g., a spring tension acts upon the regulator la a constant quantity of liquid is additionally fed to the passage with every load, as illustrated by the lines b, b, b. In this diagram the distance 12 corresponds to the force which additionally acted upon the regulator I8. In this instance the middle position of the ratio slider l8 corresponds to the characteristic 1), so that by a convenient adjustment of the ratio slider the characteristic b may be obtained, according value reaches the value at upon a load of zero. Moreover, by giving the cam 22 a suitable form the ratio: water inflow-vapor outflow may be varied at will as represented by lines 0, c', in order to adapt said ratio to the type of the vapor generators.

A well known water level regulator 23 is provided for actuating a valve 24 being incorporated in a conduit 25. The conduit 25 is connected to the lower part of the drum 1 and to the feeding pump 2. By means of the water level regulator 23 the water level 1 is maintained constant and the water additionally fed to the passage I is returned to the pump 2 without influencing the feeding regulator [8.

Having thus described my invention and one embodiment thereof, I desire to be distinctly understood that I am not to be limited thereby except as to the claims in view of prior art.

What I claim is:

1. Apparatus for automatically controlling the operation of a vapor generator having a fluid passage receiving liquid at one end and delivering superheated vapor at the other end and heated by elements of combustion comprising, in combination, a drum inserted in the zone of evaporation of said passage, means responsive to the pressure in said drum, a valve inserted in the vapor part of said passage and connected to be controlled by said pressure responsive means for maintaining a constant pressure in said drum, impulse means responsive to the pressure difference between the pressure to be maintained constant in said drum and the pressure at a point of measurement taken at the end of the superheated vapor part of said passage, liquid supply control means connected to be actuated by said impulse means for varying the liquid inflow in response to the generator load variations.

- 2. Apparatus as claimed in claim 1, in which said valve'for maintaining a constant pressure in said drum is arranged in the steam consumption conduit communicating with the superheated vapor delivering end of said fluid passage and leading to a steam consumption device.

3. Apparatus for automatically controlling the operation of a vapor generator having a fluid passage receiving liquid at one end and delivering superheated vapor at the other end and heated by elements of combustion comprising, in combinationya liquid separator inserted in the zone of evaporation of said passage, means of supplying liquid to said passage, a liquid supply control valve, a servo-motor for actuating said valve, a relay for controlling said servomotor, impulse means responsive to the generator load variations connected to actuate said relay, means for exerting an additional superfeed control force on said relay and means for varying said superfeed control force in accordance with the desired superfeed value.

CARL SCHROEDER. 

